This is largely achieved by preventing all undergraduates (and most GradStudents?) from knowing about it. Hence the looks of surprise or disgust which one acquires upon attempting to discuss the CambridgeUnderground with students.
But think about it: how do you think all those lecturers get to the department on time?? There are very few Fellows who are ever seen on the streets of Cambridge, or on their way to departments.
Now imagine an Underground system, whose very existence is hushed up and kept secret from the vast majority of Cambridge inhabitants. Stops in all the major departments like the Cockcroft?, CavendishLabs, SidgwickSite, etc; in several colleges (two stops in TrinityCollege, of course); and in a variety of other convenient locations. Places which dip underground mysteriously, but where most students wouldn't venture, for one reason or another.
It's a solution which epitomises Cambridge.
So, it's not a resistance movement then? --Tsunami
The Cambridge Underground is as described on this page; nothing more, nothing less.